In pumping fluids from a well, certain difficulties may arise depending upon the nature of the fluids being extracted. For the purposes of this disclosure, the particular problems addressed are those which occur when the fluids in the well contain particulate matter such as sand. This particulate matter, especially if it is sand, tends to abrade the working surfaces, such as pump plungers and valves, with which the particulate matter comes into contact. Another problem caused by particulates, such as iron sulfides or other fine grain materials, occurs when such particulates adhere to the moving parts of a pump causing those parts to stick and if unchecked, to eventually bind or tie up completely. As a result, the working lifetimes of fluid production pumps are often significantly shortened by the abrasive and/or adhesive actions of the particulate bearing fluids being pumped thereby.
Various sand or other particulate straining or filtering devices are commercially available, however, many of these suffer drawbacks. The most important drawbacks are those which affect the quantity of fluid being produced. For example, various straining or filtering devices, by their nature significantly reduce the speed of fluid movement and hence, reduce the quantity of fluid being produced. Another example involves the significant downtimes which occur while well production tubing or rod strings are pulled for cleaning or replacing the attached strainer or filter. The pulling of conventional strainers or filters is required in order to remove clogging particulates from such devices or to replace the device because many of such strainers or filters are simply not reusable once clogged.
A few prior attempts to solve some of these problems are described in my prior patent, U.S. Pat. No. 5,295,537. However, these are also somewhat disadvantageous due, in part, to their complexity and restrictive attachability solely to the production tubing. Therefore, there remains a need to provide an improved particulate separator for fluid production wells which will maintain, if not increase the fluid production of a well while also reducing the downtime required to pull and replace damaged pumps or to clean or replace clogged straining or filtering devices.